Hereinafter, the term “switching control device” denotes any switch and/or control device(s) with which an operator can switch, or control in some other way (including in an analog way) a function of the instrument in question, especially an energy supply thereto, a geometric configuration thereof or a signal transmission there-from. An “instrument” should be understood to mean any medical—surgical, therapeutic or diagnostic—instrument and “manipulating part” denotes parts or sections of an instrument of this kind, which an operator holds in the hand and/or on which he/she performs switching or control functions when the instrument is used for medical purposes.
The reusable surgical manipulating elements having an activation function (e.g., electrode handles for HF surgery) currently available on the market are designed such that the switching function or the electronic components required therefore (such as, e.g., push buttons, resistances, diodes) are mounted on a printed circuit board, which is integrated centrally in the interior of the handles.
The electrical cable connections (litz wires) are usually soldered onto the printed circuit board. The contact socket required for the electrical and mechanical contacting of the instruments (e.g., monopolar electrodes) is also attached to the printed circuit board (e.g., by soldering). In the case of HF surgery handles, the power required for use is thus supplied via the conductors mounted on the printed circuit board.
Surgical manipulating elements with an activating function (e.g., electrode handles for HF surgery) are prepared by sterilization using moist heat, ethylene oxide gas or gamma radiation. It is necessary to ensure that the products fulfill their function over a defined period without any restriction and that no safety-relevant defects posing a risk to the patient and user occur thereby. The ambient conditions (thermal, physical) of the different sterilization methods can result in the premature failure of the products, e.g., due to the penetration of fluids.
To maintain a fault-free function and exclude safety-relevant defects, it is necessary to prevent the penetration of moisture (initiated by preparation: washing, sterilization). This is generally achieved by mechanical seals (e.g., O-rings) at the interfaces to the external environment (e.g., cable outlet, button region, contact socket region on the distal end of the handle).
The structural principles of the activating function for different surgical manipulating elements can sometimes differ greatly and consequently, the maintenance of the defined lifetime in accordance with the safety requirements can turn out very differently.
The known solutions to prevent the penetration of moisture during the preparation, washing or sterilization of the instruments or manipulating parts have certain systemic drawbacks:
Mechanical sealing of the numerous interfaces is difficult to achieve, especially due to material changes induced by chemical/thermal reconditioning. The sealing elements are exposed to extreme stress due to the “tight system” and trapped air (in large hollow spaces), thermal cycling and the corresponding gas exchange in the interior of the handles (initiated by the washing and sterilization processes). The penetration of moisture can cause corrosion of metallic parts (especially conductors, contacts, connections between electronic components), which can result in a functional failure and, in the “worst case,” to self-activation. Especially with HF conducting structures, the penetration of moisture can result in corrosion initiated by electrochemical processes, which can have extremely serious consequences from both functional and safety viewpoints.